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Flashcards in Session 9 Deck (33)
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1

What is Pharmacokinetics?

What the body does to a drug

2

What are the 2 formulations of a drug?

Solid
Liquid

3

If the drug is a solid, what does rate of action depend on?

Dissolution

4

What are the sites of administration?

Local (eg oral, rectal)
Systemic - Enteral (Sublingual) Parenteral (IV, inhalation)

5

What is the advantage of local administration of drugs?

There are high concentrations of the drug at the site
There are less systemic effects

6

What is Oral Bioavailability?

Proportion of dose given orally (or any other route except IV) that reaches the systemic circulation in an unchanged form

7

How can Bioavailability be expressed?

Amount
Rate

8

How can you calculate the Bioavailability of a drug?

Area under curve for oral /
Area under curve for injection
x100

9

What is the Therapeutic ratio?

Maximum tolerated dose (L50) /
Minimum effective dose (ED50)

10

Is a low or high Therapeutic ratio desirable?

High because this means the desired curve is far from the side effects curve

11

What is the First Pass effect?

A substance absorbed through the Ileum will enter the venous blood and passes directly to the liver where it is extensively metabolised before reaching the rest of the body.

12

Which routes can avoid the First Pass effect?

Parenteral
Sublingual
Rectal

13

What is Drug Distribution?

Theoretical volume into which a drug has distributed assuming that this occurs instantaneously

14

How can you calculate Drug Distribution?

Amount given /
Plasma concentration at time 0

15

What exerts the effects of a drug?

The level of free drug in the blood

16

What is the main plasma protein that drugs can bind to?

Albumin

17

When are protein binding actions important?

Drugs highly bound to albumin
Drug have a small volume of distribution
Drug has low therapeutic index

18

What is an Object (Class I) drug?

It is the drug that is medically active. It is used at a concentration which is much lower than the number of albumin binding sites

19

What is a Precipitant (Class II) drug?

The drug that is used at higher concentrations (Than the available binding sites) to displace the Class I drug from albumin.

20

What is the precipitant drug for Warfarin?

Aspirin
Sulphonamides

21

What is First order Kinetics?

The metabolism of the drug is proportional to drug concentration. Half life can be defined.

22

What would you see on a graph for First order Kinetics?

A straight line when a log scale is on the Y axis Vs time.

23

What is Zero order Kinetics?

Rate of elimination is constant regardless of concentration.

24

What would you see on a graph for Zero order Kinetics?

Straight line when normal (not log) plasma concentration is plotted against time (X)

25

How many half lives does it take for drug to reach a steady state?

5 half lives for all drugs regardless of dose or frequency

26

What is needed for an immediate effect of a drug?

A loading dose

27

How can you determine the loading dose?

Volume of distribution

28

What is the difference between First order Kinetics and Zero order kinetics?

First order gives a predictable Therapeutic response from dose increases
Zero order kinetics give a therapeutic response that can suddenly escalate as elimination mechanism saturate

29

What are some examples of Cytochrome P450 enzyme inducers?

Cigarettes (effects Theophylline drug)
Rifampicin (effects OC pill)

30

What is an example of Cytochrome P450 enzyme inhibitors?

Cimetidine (effects Warfarin drug)